Thread-cutting machines



July 2, 1957 R RENO X 2,797,601

THREAD-CUTTING MACHINES Filed March 18, 1953 5 Sheets-Sheet 1 ITS y 1957P. E. RENOUX 2,797,601

THREAD-CUTTING MACHINES Filed March 18, 1955 5 She'ets-Sheet 2 "VZJJM4/. 62M

July 2, 1957 Filed March 18, 1953 P. E. RENOUX THREAD-CUTTING MACHINES 5Sheets-Sheet 3 GEM/95L. WM 40. 62M,

July 2, 1957 P. E. RENOUX 2,797,601

THREAD-CUTTING MACHINES Filed March 18, 1953 5 Sheets-Sheet 5 UnitedStates Patent or ice THREAD-CUTTING MACHINES Pierre Edouard Renoux,Argcntenil, France, assignor to Societe Anonyme dite: Cri-Dan, Paris,France, a French company Application March 18, 1953, Serial No. 343,178

Claims priority, application France January 13, 1953' 4 Claims. (Cl. 82-5) It has already been proposed in semi-automatic threadcutting.machines operating through the removal. of turnings by means of a simpletool executing a succession of cuts, to produce the longitudinalalternating translational movement of the tool by means of a cam, termedthe pitch cam, assuming a continuous rotary movement, the main sectionof the cam outline producing the progression of the tool in a givendirection corresponding to the active stage of the cutting, while theremaining section of the outline. corresponds to the speedy return ofthe tool.

Generally, the longitudinally movable carriage supporting the transversecarriage on which the tool is fitted and that is controlled by the pitchcam, is urged into contact with the latter with the interposition of acontact member such as a roller, which is urged by a spring against thecam.

The progression of the cutting tool during the operative stages of thecutting is performed generally in a direction urging the tool towardsthe spindle or the headstock of the machine tool.

Now, it may be of advantage. in certain cases to produce the threadthrough a reversal of the direction of said operative stages, i. e. toproduce the turningswhile the tool moves away from the head-stock. Thismethod of operating allows in. particular automatically releasing theturnings during the execution of a tapping.

In other cases, it :allows holding the tool in the same position,whatever may be the direction of the thread produced, whether providedwith a right hand pitch or with a left hand pitch, which leads'tokeeping a predetermined direction for the cutting stress, whichcondition is favorable for increasing the life and accuracy of themachine.

This effect may obviously be obtained through a mere reversal of thedirection of rotation of the machine as provided e. g. by making itsmotor revolve in reverse direction; but this would result in a reversalof the tool reactionsand of the friction exerted in the slideways and,consequently, lead' to a falling out of the contact between the cam andthe member driven thereby and finally, this would be a source ofinaccuracy and even of damage to the'work that is being executed.

It is also possible to supply the machine with two series of cams to beused respectively for left hand threadcutting andfor righthandthread-cutting, but this arrangement would result in a supplementaryexpense which would increase the cost price of the work produced.

Now, the present invention has for its. object to provide for theobtention of the desired result, i. e. the production of left hand andright hand thread-cutting as desired, and this is obtained by replacingthe usual pitch cam of thread-cutting machines by a reversible camadapted to be fitted selectively in two opposed positions on thecam-carrying shaft, so as to present its operative outline either in adirection producing a movement of the longitudinal carriage from rightto left e. g. and consequently, an operative movement of the tool insaid direc- 2,797,601 Patented July 2, 1957 tion or else, in theopposite direction producing a displacement of the longitudinal.carriage from left to right and consequently an operative movement ofthe tool in said direction.

The reversible cam is advantageously constituted by a hollow sleeve theperiphery of which assumes the outline of an active cam, while the endof said sleeve opposed to said cam outline is closed by a bottom sectionof which either side may serve as a bearing surface for assembling thesleeve on the end of the cam-carrying spindle in accordance with thedirection of positioning of said sleeve for producing thethread-cutting, from right to left or from left to right respectively.

The reversibility of the cam may be associated, in accordance with theinvention, with a reversibility of the tool-returning means which holdpermanently in. contact with the cam, a member. carried by thelongitudinal carriage, said. member being constituted by a roller or thelike follower.

The tool-returning means may be constituted by a single spring engagingselectively one of two stops that may recede when desired and that areprovided on the transverse carriage of the machine.

The tool-returning means may again be constituted by a double actinghydraulic or the like jack, carried by the transverse carriage and thepiston of which, rigid with the longitudinal carriage, is submittedtofiuid pressure on either of its surfaces selectively. The reversal ofthe direction of the fluid pressure on the piston-ends in the-jack maybe obtained by means of a distributor, the location of which may bedefined by that of the reversible cam.

Further features of the invention will appear in the reading of thefollowing description of various embodiments of the latter, given bywayof examples and by no means in a limiting sense, reference being made toaccompanying drawings, wherein:

Fig. 1 is a general view of a thread-cutting machine;

Figs. 2 and 3 are two diagrammatic axial cross-sections of thereversible cam carried by the cam-shaft in order to allow selectively aright-hand and a left-hand thread.- cutting;

Fig. 4 is a longitudinal sectional view of reversible means returningthe longitudinal carriage into its starting position through the agencyof a spring;

Fig. 5 is a longitudinal cross-sectional view of a modified reversiblemeans returning the longitudinal carriage into its stationary positionand operating through the agency of a hydraulic jack;

Fig. 6 is a sectional view through line VI'VI. of Fig. 5

Figs. 7 and 8 are two sectional views of the distributor feeding fiuidunder pressure to the hydraulic jack, corresponding to the cases wherethe reversible cam is positioned for thread-cutting in either directionrespectively;

and

Fig. 9 is a diagram illustrating a conventional reversible drive for camshaft 8.

Fig. 1 which is, "as stated, a general view of a threadcutting machineof conventional type, shows at 1 the frame of the machine, having aspindle 2 driving the. work in which the thread is to be cut, and acenter 3. The transversely moving carriage 4 carries a longitudinallymoving carriage 5; the cross tool carrier is shown at 6 and the pitchcam controlling the longitudinal movement of the carriage 5 is shown at7, while 8 designates the shaft controlling the rotation of the pitchcam and 9 the roller fitted underneath the end of the longitudinalmoving carriage and which is constantly urged against the pitch cam.

Figs. 2 and 3 illustrate diagrammatically a reversible cam 10 accordingto my invention; this cam is constituted by a hollow sleeve the bottomtransverse wall 11 of which has two sides, a and b, constitutingselectively, according to the manner in which the sleeve is fitted onthe camcarrying shaft 8, the surface assembling the cam with theterminal bearing section 12 of said shaft. The sleeve is provided,furthermore, at its periphery, with a camshaped outline 13 adapted to beengaged by the roller 9 carried on a spindle 14 rigid with a member 15fitted in side an arm 16 rigid in its turn with the longitudinallymoving carriage 5, said member 15 being held fast in the arm 16 by ascrew 17 engaging an annular groove 18 in said member.

According as to Whether the sleeve 10 forming the reversible cam ismounted on the camshaft 8 in a manner such that its terminal surface aor b engages the terminal surface of the bearing 12 carried by the saidshaft 8, the reversible cam 10 has its operative outline directed eithertowards the right hand side as in the case of Fig. 2, or towards theleft hand side, as shown in Fig. 3, and it produces consequently throughthe agency of the roller 9 an operative movement of the cutting toolmounted on the carriage 6 from left to right, as shown in Fig. 2, orfrom right to left, as shown in Fig. 3. The sleeve 10 forming thereversible cam may be provided with an annular recess at 19. In eitherof its positions illustrated in Fig. 2 or in Fig. 3, its central bottomsection 11 is secured to the cam shaft 8 through the agency of screws20.

It will be remarked that this positioning of the reversible cam withreference to the shaft 8 allows it to have selectively its operativesection on the right hand A side, as shown in Fig. 2, or on the lefthand side, as shown in Fig. 3, but that such a change in positionmodifies by no means the normal ends of the stroke of the longitudinalcarriage 5 corresponding to the lines G and D occupied by the axis 14 ofthe roller 9 for the two extreme positions of said roller respectively.

If A and B are the distances between the extreme outer points of theoperative outline 13 of the cam and one of the assembling surfaces a orb in either of the positions corresponding respectively to Figs. 2 and 3and if H designates the sum of said distances A and B and if, further, Ris the radius of the contact roller 9 and C the thickness of the centralbottom section 11 of the cam between the two bearing-engaging surfaces aand b, calculation shows that the following equations are true:

GX=AR and XD=B+R and in the case of Fig. 3,

GX=B+R and XD=AR-|C In both cases, the following equation isconsequently true:

and

GX+XD=GD=A+B whatever may be the location of the reversible cam on itsshaft.

The extreme positions occupied by the carriage 5 remain consequentlyunchanged when the cam 10 is reversed.

According as to whether the thread is to be cut with a left hand pitchor with a right hand pitch, the cam 10 is secured to the end of the camshaft 8 in a manner such that the surface engaging the bearing on saidshaft is either the surface a (Fig. 2) or the surface b (Fig. 3).

By reason of this relative positioning, it is possible to obtain thedesired effect by means of a single cam without inserting any furthermember for the drive of r 4 the longitudinal carriage 5 and without anymodification in the extreme positions of the latter.

The reversal of the cam 10 implies, of course, a reversal of itsdirection of rotation.

The roller 9 on the movable carriage 5 which is controlled by therotation of the cam 10, may be held fast permanently in contact with thelatter through the agency of a spring 21 having a reversible action, asillustrated in Fig. 4 and as described hereinafter.

The transverse carriage 4 carries between two supports 22 a spindle 23fitted with two adjustable nuts and counternuts 24, 25 and 26, 27engaged normally by stops 28, 29 under the action of the compressedspring 21 wound round the spindle 23. Each stop 28, 29 is provided withan annular groove 30 adapted to be engaged by a spring-urged projection33 of the longitudinal carriage 5. A bayonet or the like system allowsholding the projection 31 or 32 raised in a receding position throughmere action on the terminal knob 34 carried by said projection, saidknob being drawn out and then rotated through one quarter of arevolution for instance. A rotation of the knob 34 by an equal amount inthe opposite direction allows releasing the latter so as to let theprojection 31 or 32 drop back into the annular groove 30 of thecorresponding stop 28 or 29.

According to the direction of the pitch to be cut, the projection 31 orthe projection 32 is brought into its receding position and thelongitudinally movable carriage 5 controlled by the rotation of the cam10 is held in contact with the latter through the follower 9 by thespring 21 acting on said carriage through the agency of the stop 29 orof the stop 28, as the case may be. In Fig. 4, it has been assumed thatthe pitch was being cut from right to left and that the carriage 5 washeld in contact with the cam 10 through the agency of the spring 21 andof the stop 29, moving in unison with said carriage by reason of theprojection 32 engaging said stop.

In Fig. 5, the reversible tool and carriage-returning means urging thecarriage against the roller 9 contacting with the cam 19 include adouble acting hydraulic jack. This jack includes a stationary cylinder35 rigid with the transverse carriage 4 and inside which may move apiston 36 carried by a rod 37 passing through the bottom of the cylinder35 and engaging a member 38 rigid with the movable carriage 5.

39 and 40 designate pipes feeding fluid under pressure into the cylinder35 near the corresponding ends thereof, so as to act selectively on theopposite surfaces of the piston 36. The piston 36 is driven in unisonwith the carriage 5 rigid therewith towards the right hand side ortowards the left hand side, whenever the fluid under pressure actscorrespondingly on the left hand side or on the right hand side of thepiston 36.

The direction of the thrust thus exerted on the piston 36 and,consequently, on the carriage 5 rigid with said piston, by thecompressed fluid, may be reversed through the operation of the four-waydistributor illustrated in Figs. 6 to 8. Insaid figures isshown thecam-carrying shaft 8 with its reversible cam 10, said cam being assumedin the case of Fig. 7 as positioned for left-to-right thread cutting andin Fig. 8 for right-to-left thread cutting. 9 designates again theroller carried by the longitudinally movable carriage 5 for engagementwith said cam 10.

To the frame 41 supporting the camshaft 8 is secured the body 42 of adistributing cylinder inside which may move a piston 43 provided with anannular peripheral recess 44 and with an axial bore 45 subdivided intotwo arms 46 diverging to either side of a rod 47 rigid with the piston43. Said rod 47 is rigid with a terminal strap 48 on the outside of thecarrying frame 41, said strap carrying a spindle 49 to which isrevolubly secured a roller 50.

' The roller 50 may, for the position of the reversible cam 10 shown inFig. 7, roll over the rear end of the said 5 reversible cam 10. A coilspring 51- urges constantly the piston 43 towardsthe right hand side ofFigs. 7 and 8'.

The cylinder 42 is provided with ports 53, 54, 55' and 56 communicatingrespectively with the pipes 39' and 40 opening: into the cylinder 35 ofthe hydraulic jack, with a pipe 57 feeding fluid under pressure andfinally with a pipe 58 serving for the exhaust of said fluid.

In the position occupied by the distributing piston 43, as illustratedin Fig. 7, and corresponding to a drive towards the right hand side ofthe movable carriage 5 under the action of the cam 10, the fluid underpressure admitted through the pipe 57 passes through the port 56 intothe annular recess 44 and thence through the port 53 and the pipe 39into the cylinder 35 of the jack so as to act on the right hand side ofthe piston 36, which urges thus constantly the roller 9 carried by themovable carriage 5 against the reversible cam 10 during the displacementof said carriage. The fluid under pressure contained in the cylinder onthe other side of the piston 36 is exhausted through the pipe 40 and theports 54, 46, and 55 into the exhaust pipe 58.

In Fig. 8, the movable carriage 5 is assumed to have been driven towardsthe left hand side by the reversible cam 10 that is positionedcorrespondingly while the spring 51 has urged into its extreme righthand position the strap 48 with the roller 50 thereon and thedistributor piston 43. The fluid under pressure acts then on the lefthand side of the jack piston 36 through the agency of the port 56, ofthe annular recess 44, of the port 54 and of the pipe 40, while thefluid under pressure is exhausted away from the other side of the piston36 through the pipe 39, the ports 53 and 55 and the exhaust pipe 58.

While various reversible drives may be provided for cam shaft 8, asatisfactory arrangement is diagrammed in Fig. 9 wherein is illustrateda reversible electric motor energized by a source 62 of three-phasevoltage to which it is coupled through a reversing switch 64, it beingapparent that motor 60 will rotate in the selected rotative direction inaccordance with the position of reversing switch 64. Speed gearing 66coupled by belt 68 to motor 60 and speed-controlled by lever 70 has itsdrive shaft 72 geared as at 74 to cam shaft 8, so that cam 10 is rotatedin one direction or the other in accordance with the position ofreversing switch 64.

The present invention covers also a thread-cuttting machineincorporating at least part of the above disclosed improvements insofaras they are claimed in accompanying claims.

What I claim is:

1. In a thread-cutting machine, a frame; a tool carriage supported onsaid frame for sliding movement in opposite longitudinal directions; acamshaft rotatably mounted with its longitudinal axis extendinglongitudinally of the direction of movement of the carriage, means forselectively rotating said camshaft in either of its two oppositerotative directions; a cam comprising a substantially sleeve-shaped bodyhaving a cam surface at one end; means for mounting said body on saidcamshaft selectively in either of two positions, in the first of whichpositions said cam surface faces one axial direction of the cam shaftand in the second of which said positions said cam surface faces theopposite axial direction, a cam follower on said carriage, said camfollower being adapted to engage said cam surface when the latter ismounted in either of said positions, whereby said carriage is positivelydriven in said one longitudinal direction or the other in accordancewith the selected mounting of said cam on said camshaft; and reversiblebias means engaged between said frame and said carriage for selectivelybiasing said carriage contra to the direction of positive drive of saidcam, whereby to return said carriage in the direction opposite to thepositive drive thereof.

2. In a thread-cutting machine, a frame; a transverse carriagetransversely shiftable on said frame; a tool carriage supported on saidtransverse carriage for sliding movement in; opposite directionslongitudinally of the frame; a cam shaft rotatably mounted on saidtransverse carriage with its longitudinal axis extending longitudinallyof the direction of movement of the tool carriage, means for selectivelyrotating said shaft in either of its two opposite rotative directions; acam comprising a substantially sleeve-shaped body having a cam surfaceat one end; means for mounting said cam on said camshaft selectively ineither of two positions, in the first of which positions said camsurface faces one axial direction of the camshaft and in the second ofwhich said positions said cam surface faces the opposite axialdirection; a cam follower on said carriage; said cam follower beingadapted to engage said cam surface when the latter is mounted in eitherof said positions, whereby said carriage is positively driven in saidone longitudinal direction or the other in accordance with the selectedmounting of said cam on said camshaft; and a double-acting jackincluding a cylinder member and a piston member, one member beingmounted on said transverse carriage and the other member being mountedon said tool carriage; and means for feeding fluid to said cylindermember selectively on either side of said piston member, whereby to holdsaid cam follower against said cam surface and to return said carriagein the direction opposite to the direction in which it is positivelydriven by said cam.

3. The combination claimed in claim 2, the means for selectively feedingfluid to said cylinder member on either side of said piston membercomprising a pair of fluid pipes leading respectively to opposite sidesof said cylinder member, fluid supply and return conduits, a multi-waydistributor valve connected to said pipe and conduits and selectivelyactuatable for establishing fluid flow from said supply conduit toeither one of said pipes while simultaneously establishing communicationbetween the other pipe and the return conduit, and means engaging saidcam body responsive to the position thereof on said camshaft foractuating said distributor valve.

4. In a thread-cutting machine, a frame; a transverse carriagetransversely shiftable on said frame, a tool carriage supported on saidtransverse carriage for sliding movement in opposite directionslongitudinally of the frame; a camshaft rotatably mounted on saidtransverse carriage with its longitudinal axis extending longitudinallyof the direction of movement of the tool carriage; means for selectivelyrotating said camshaft in either of its two opposite rotativedirections; a cam comprising a substantially sleeve-shaped body having acam surface at one end; means for mounting said cam on said camshaftselectively in either of two positions, in the first of which positionssaid cam surface faces one axial direction of the camshaft and in thesecond of which said positions said cam surface faces the opposite axialdirection of the camshaft; a cam follower on said carriage, said camfollower being adapted to engage said cam surface when the latter ismounted in either of said positions, whereby said carriage is positivelydriven in said one longitudinal direction or the other in accordancewith the selected mounting of said cam on said camshaft; an elongatecompression spring mounted on said transverse carriage with its lengthextending longitudinally of the direction of movement of said toolcarriage; a pair of abutments on said transverse carriage respectivelyadjacent opposite end portions of said spring and adapted to be engagedthereby;

and independently operable catch means longitudinally spaced along saidtool carriage, said catch means being respectively engageable with theopposite end portions of said spring, whereby a selected one of saidcatches may be engaged with one end portion of said spring so that thespring is compressed between the selected catch and the abutment at theopposite end portion of the spring as a result of the positive drive ofsaid cam.

(References on following page) 7 8 References Cited in the file of thispatent 1 2,417,091 Smith Mar. 11, 1947 2,462,126 Peat Feb. 22, 1949UNITED STATES PATENTS 2,468,478 Ardoin Apr. 26, 1949 1,454,554 M1tche1lMay 8, 1925- 2,527,397 Castelli Oct. 24, 1950 2,291,591 Medholdt July28, 1942 5 2,627,618 Holmes Feb. 10, 1953

